doc: Removed the RedHat part from the "run all tests with docker " tutorial, because I could not find a reliable source.
doc: Removed the RedHat part from the "run all tests with docker " tutorial, because I could not find a reliable source.

ElektraInitiative/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,mpranj/libelektra,mpranj/libelektra,mpranj/libelektra,ElektraInitiative/libelektra,ElektraInitiative/libelektra,mpranj/libelektra,mpranj/libelektra,mpranj/libelektra,ElektraInitiative/libelektra